To effect behavior change, it is not sufficient simply to establish desirable behavior. It is also necessary that the behavior persist after therapy ends, and that it be appropriate to the circumstances of daily life. This entails learning to discriminate relations between situations, behavior, and consequences, and these discriminative processes must also be persistent. This project will explore the persistence of discriminative processes including attention, memory. and sensitivity to consequences. Previous research has found that the resistance to change of simple repeated behavior depends directly on the frequency or magnitude of reward, but there is no systematic information on the role of reward in the resistance to change of discriminative processes. To obtain relevant data, pigeons will be trained on delayed matching to sample and related tasks where food rewards for one of two simultaneously available choice responses are signaled by one of two successive stimuli. Different frequencies of food rewards will he arranged in successive components of experimental sessions. Responding that produces discrimination trials will also be measured. After prolonged training, the resistance to change of response rate and of learned stimulus-behavior and behavior-consequence relations will be evaluated by introducing short-term disruptors. The long-term goal of this project is to determine whether discriminative processes and simple response emission depend similarly on reward conditions. If so, the same behavioral principles that have been successful in establishing durable new behavior can be used to develop persistent discriminative processes in clinical populations.